Are we humans simply remodelled apes? Chimps with a tweak? Is the difference between our genomes so minuscule it justifies the argument that our cognition and behaviour must also differ from chimps by barely a whisker? If “chimps are us” should we grant them human rights? Or is this one of the biggest fallacies in the study of evolution? NOT A CHIMP argues that these similarities have been grossly over-exaggerated - we should keep chimps at arm’s length. Are humans cognitively unique after all?
Wednesday, 14 April 2010
Disruption Of Temporoparietal Junction Affects Moral Judgements
In my chapter INSIDE THE BRAIN I mention the work of Rebecca Saxe and her belief that an area of the brain known as the temporoparietal junction was extremely important in the capacity to infer mental states - beliefs, desires etc. - in other people and thus tremendously important to our ability to form moral judgements that depend on our assessment of others' mental states. In this paper, together with Marc Hauser and others, she reports that, when the TPJ was disrupted using transcranial magnetic stimulation, subjects were much less able to make moral distinctions between intentional versus accidental harm. They judged attempted harms as less morally forbidden and more morally permissable than control individuals.
Tuesday, 13 April 2010
Empathy And Violence Have Similar Circuits In The Brain
During my various stumps around the country giving talks to various branches of Cafe Scientifique I often refer to the inordinate evolution of parts of the brain in humans that we associate with social intelligence and I'm often asked, at question time, why, if we have evolved greater propensities than apes for social intelligence, tolerance, culture etc. etc. are we also capable of our own extremes of violence? Part of the answer might come from this Physorg article which suggests that key components of the social brain, involved in empathy - like the prefrontal and temporal cortices, the amygdala, insula and cingulate cortex - overlap in a surprising way to those circuits that regulate violence and aggression. Whomever translated the article from the original Spanish did a poor job - resulting in some amusing mistakes, and the researchers' own conclusions, that this may help train brains to be more empathic, are just plain silly. Nevertheless, the piece is probably worth noting.
Changes In DNA Sequences That Do Not Produce Protein Are Important For Human Brain Evolution
In my chapter THE RIDDLE OF THE 1.6% I present plenty of evidence that evolutionary changes to parts of the genome that regulate gene expression (rather than DNA sequence change inside those genes) has an important role to play in human evolution, particularly of the brain and cognition. And this fact - beautifully, and recently, established by Ralph Haygood and colleagues, explains why two species - humans and chimps - that differ so little at the level of DNA sequence can be so different over many parameters. Now this same team have taken another wide-angle look at the human genome and have established strong correlations between evolution of non-coding regulatory sequences of DNA and gene expression "indicating that neural development and function have adapted mainly through non-coding changes...whereas adaptation via coding changes (evolution inside genes) is dominated by immunity, olfaction and male reproduction."
Genes that are highly tissue-specific in terms of where they are expressed are more likely to undergo sequence evolution than genes more widely expressed in several tissues. The authors suggest that, since genes work in teams such that any one gene may affect various aspects of the phenotype of an organism (this is called pliotropy) this constrains sequence evolution in genes (potentially throwing a spanner into complex machinery) in favour of gene expression changes. They conclude: "Our findings underscore the probable importance of non-coding changes in the evolution of human traits, particularly cognitive traits."
Genes that are highly tissue-specific in terms of where they are expressed are more likely to undergo sequence evolution than genes more widely expressed in several tissues. The authors suggest that, since genes work in teams such that any one gene may affect various aspects of the phenotype of an organism (this is called pliotropy) this constrains sequence evolution in genes (potentially throwing a spanner into complex machinery) in favour of gene expression changes. They conclude: "Our findings underscore the probable importance of non-coding changes in the evolution of human traits, particularly cognitive traits."
First Direct Evidence Of Mirror Neurons In Human Brains
In my chapter INSIDE THE BRAIN I mention the fact that the presence of mirror neurons in human brains is hotly disputed in some quarters because of the lack of the sort of direct evidence from probes into the brain that has been garnered from monkeys. Researchers looking at human brains have had to use non-invasive techniques to infer the action of mirror neurons. However, as this report shows, if you have access to deep-implanted electrodes put into human brains to help treat conditions like Parkinsons and epilepsy, you can "piggyback" mirror neuron research. And then you find them...Here's the physorg article in entirety:
"Mirror neurons, many say, are what make us human. They are the cells in the brain that fire not only when we perform a particular action but also when we watch someone else perform that same action.
Neuroscientists believe this "mirroring" is the mechanism by which we can "read" the minds of others and empathize with them. It's how we "feel" someone's pain, how we discern a grimace from a grin, a smirk from a smile.
Problem was, there was no proof that mirror neurons existed — only suspicion and indirect evidence. Now, reporting in the April edition of the journal Current Biology, Dr. Itzhak Fried, a UCLA professor of neurosurgery and of psychiatry and biobehavioral sciences, Roy Mukamel, a postdoctoral fellow in Fried's lab, and their colleagues have for the first time made a direct recording of mirror neurons in the human brain.
The researchers recorded both single cells and multiple-cell activity, not only in motor regions of the brain where mirror neurons were thought to exist but also in regions involved in vision and in memory.
Further, they showed that specific subsets of mirror cells increased their activity during the execution of an action but decreased their activity when an action was only being observed.
"We hypothesize that the decreased activity from the cells when observing an action may be to inhibit the observer from automatically performing that same action," said Mukamel, the study's lead author. "Furthermore, this subset of mirror neurons may help us distinguish the actions of other people from our own actions."
The researchers drew their data directly from the brains of 21 patients who were being treated at Ronald Reagan UCLA Medical Center for intractable epilepsy. The patients had been implanted with intracranial depth electrodes to identify seizure foci for potential surgical treatment. Electrode location was based solely on clinical criteria; the researchers, with the patients' consent, used the same electrodes to "piggyback" their research.
The experiment included three parts: facial expressions, grasping and a control experiment. Activity from a total of 1,177 neurons in the 21 patients was recorded as the patients both observed and performed grasping actions and facial gestures. In the observation phase, the patients observed various actions presented on a laptop computer. In the activity phase, the subjects were asked to perform an action based on a visually presented word. In the control task, the same words were presented and the patients were instructed not to execute the action.
The researchers found that the neurons fired or showed their greatest activity both when the individual performed a task and when they observed a task. The mirror neurons making the responses were located in the medial frontal cortex and medial temporal cortex, two neural systems where mirroring responses at the single-cell level had not been previously recorded, not even in monkeys.
This new finding demonstrates that mirror neurons are located in more areas of the human brain than previously thought. Given that different brain areas implement different functions — in this case, the medial frontal cortex for movement selection and the medial temporal cortex for memory — the finding also suggests that mirror neurons provide a complex and rich mirroring of the actions of other people.
Because mirror neurons fire both when an individual performs an action and when one watches another individual perform that same action, it's thought this "mirroring" is the neural mechanism by which the actions, intentions and emotions of other people can be automatically understood.
"The study suggests that the distribution of these unique cells linking the activity of the self with that of others is wider than previously believed," said Fried, the study's senior author and director of the UCLA Epilepsy Surgery Program.
"It's also suspected that dysfunction of these mirror cells might be involved in disorders such as autism, where the clinical signs can include difficulties with verbal and nonverbal communication, imitation and having empathy for others," Mukamel said. "So gaining a better understanding of the mirror neuron system might help devise strategies for treatment of this disorder."
Provided by University of California - Los Angeles
"Mirror neurons, many say, are what make us human. They are the cells in the brain that fire not only when we perform a particular action but also when we watch someone else perform that same action.
Neuroscientists believe this "mirroring" is the mechanism by which we can "read" the minds of others and empathize with them. It's how we "feel" someone's pain, how we discern a grimace from a grin, a smirk from a smile.
Problem was, there was no proof that mirror neurons existed — only suspicion and indirect evidence. Now, reporting in the April edition of the journal Current Biology, Dr. Itzhak Fried, a UCLA professor of neurosurgery and of psychiatry and biobehavioral sciences, Roy Mukamel, a postdoctoral fellow in Fried's lab, and their colleagues have for the first time made a direct recording of mirror neurons in the human brain.
The researchers recorded both single cells and multiple-cell activity, not only in motor regions of the brain where mirror neurons were thought to exist but also in regions involved in vision and in memory.
Further, they showed that specific subsets of mirror cells increased their activity during the execution of an action but decreased their activity when an action was only being observed.
"We hypothesize that the decreased activity from the cells when observing an action may be to inhibit the observer from automatically performing that same action," said Mukamel, the study's lead author. "Furthermore, this subset of mirror neurons may help us distinguish the actions of other people from our own actions."
The researchers drew their data directly from the brains of 21 patients who were being treated at Ronald Reagan UCLA Medical Center for intractable epilepsy. The patients had been implanted with intracranial depth electrodes to identify seizure foci for potential surgical treatment. Electrode location was based solely on clinical criteria; the researchers, with the patients' consent, used the same electrodes to "piggyback" their research.
The experiment included three parts: facial expressions, grasping and a control experiment. Activity from a total of 1,177 neurons in the 21 patients was recorded as the patients both observed and performed grasping actions and facial gestures. In the observation phase, the patients observed various actions presented on a laptop computer. In the activity phase, the subjects were asked to perform an action based on a visually presented word. In the control task, the same words were presented and the patients were instructed not to execute the action.
The researchers found that the neurons fired or showed their greatest activity both when the individual performed a task and when they observed a task. The mirror neurons making the responses were located in the medial frontal cortex and medial temporal cortex, two neural systems where mirroring responses at the single-cell level had not been previously recorded, not even in monkeys.
This new finding demonstrates that mirror neurons are located in more areas of the human brain than previously thought. Given that different brain areas implement different functions — in this case, the medial frontal cortex for movement selection and the medial temporal cortex for memory — the finding also suggests that mirror neurons provide a complex and rich mirroring of the actions of other people.
Because mirror neurons fire both when an individual performs an action and when one watches another individual perform that same action, it's thought this "mirroring" is the neural mechanism by which the actions, intentions and emotions of other people can be automatically understood.
"The study suggests that the distribution of these unique cells linking the activity of the self with that of others is wider than previously believed," said Fried, the study's senior author and director of the UCLA Epilepsy Surgery Program.
"It's also suspected that dysfunction of these mirror cells might be involved in disorders such as autism, where the clinical signs can include difficulties with verbal and nonverbal communication, imitation and having empathy for others," Mukamel said. "So gaining a better understanding of the mirror neuron system might help devise strategies for treatment of this disorder."
Provided by University of California - Los Angeles